Preparation key to successful screening

Compared with the colon cleansing preparation, a colonoscopy is a breeze. The preparation is uncomfortable and time-consuming but mandatory for a successful screening.

The most important advancement in preparation is split dosing, drinking one half of the prep solution the night before and the second half the next morning.

“It does a better job of cleaning out the bowel, and most people tolerate it better,” said Dr. Edward Paredez, chief of gastroenterology at Scripps Memorial Hospital in La Jolla. “The split bowel preparation is now the gold standard.”

The following colonoscopy preparations are used today. Talk to your doctor about which one is best for you.

• Polyethylene glycol (PEG) preps: These electrolyte-balanced solutions are supposed to be consumed in about one-gallon amounts before a colonoscopy. It has been found that the products are most effective if about half is consumed the night before and the other half a few hours before the screening. Brand names include Golytely, Colyte, Nulytely, Trilyte and Halflytely.

PEG solutions contain large amounts of MiraLAX, an over-the-counter constipation treatment, and salts to prevent patients from getting dehydrated by diarrhea. PEG solutions work by pushing a large volume of fluid through the bowel to force out waste. They cause no significant electrolyte shifts, so they are considered safer than OSP solutions (see below). The salty taste may be unpalatable, and the large fluid volume can cause nausea, vomiting, bloating and cramping.

• Oral sodium phosphate (OSP) tablets: Patients take about 32 tablets, available by prescription, along with drinking 64 ounces of clear liquids. Some reports say OSP tablets are as effective as PEG and may be more tolerable. However, they may cause dehydration and electrolyte imbalances in some people. Brand names include Visicol and OsmoPrep.

Over-the-counter oral sodium phosphate products were withdrawn from the market after the FDA warned in 2008 that they were associated with acute phosphate nephropathy, which can result in kidney failure and a lifetime of dialysis.

• Gatorade prep: People who drank a mixture of 64 ounces of Gatorade with 306 grams of MiraLAX experienced less bloating and cramping compared with those who prepped using a traditional solution, according to a recent study published in the journal Clinical and Translational Gastroenterology. MiraLAX flushes electrolytes from the body so pairing it with Gatorade or a similar drink helps maintain electrolyte balance, according to the study.

Because the solution is better tolerated than other commercial preps, patients are able to drink most of it, adequately cleaning their colon. However, the Gatorade prep is not approved by the FDA so many doctors don’t recommend it to their patients.

• Prepopik: Approved by the FDA last summer for cleansing the colon, Prepopik requires drinking 10 ounces of an oral solution, 5 ounces at night and 5 more ounces the morning before the exam. Though touted as a low-volume option, it still must be taken with an additional 64 ounces of other fluids.

Prepopik, a combination of magnesium oxide and citric acid with sodium picosuflate, isn’t widely available in the United States. Moreover, the studies showed that it did not cleanse the colon as well as some other methods, and many patients do not like the taste of magnesium citrate. Side effects can include headaches, nausea and vomiting.

Prepopik is not safe for all people. Those with kidney problems should not use it and there is no evidence that it is safe for pregnant women, so they shouldn’t take it unless explicitly advised by their physician.